The studies covered the Wymój, Sarąg, Łęguty and Isąg lakes with the Pasłęka river flowing through, and their drainage basins. It was found that the lakes of upper Pasłęka fall into degradability category II, i.e. they are moderately susceptible to eutrophication. Their drainage basins, having a great potential for supplying matter to the reservois, were included in basin category 4. The lakes with their drainage basins belong to the 2nd type of lake–drainage basin ecosystems in which the unfavourable basin conditions (high potential for solid matter supply) are balanced by the relatively high lake’s resistance to external impacts. In such a system the natural eutrophication of the lake is expected to proceed at a moderate rate. The upper Pasłęka lakes, however, show an accelerated rate of this process, which is mostly due to the high load of biogenic compounds supplied by the river and the intensive recreational use of the lakes.

99-111